Fig 1.
Morphological differences between OB and OS on Ashdown’s agar.
(A & B) OB colonies were visible after 24 hours of incubation, and continued to grow larger up to 48 hours of incubation. OS morphotype only appeared as small colonies after 48 hours of incubation. (C) OB showed rough, wrinkled, and irregular morphology, while OS showed smooth and round morphology after 72 hours of incubation.
Fig 2.
Histopathological changes of lungs, livers, and spleens of mice with persistent B. pseudomallei infections.
(A) Lung (B) liver and (C-E) spleen of uninfected mice show normal histopathology. (F) Non-necrotic solid lung lesions characterized by a discrete focus consisting of primarily mononuclear cells (arrow). (G) Hepatic lesion with predominantly mononuclear cells (arrow). Cytoplasmic vacuolation of hepatocytes were observed in the area surrounding the lesion, which is characterized by swelling hepatocytes and clearing cytoplasm (arrow heads) Normal hepatocyte-H. (H) Splenomegaly with large encapsulated abscess cavity (arrow). (I) The encapsulated abscess-A was surrounded by foamy macrophages-FM, epithelioid macrophages-EM, and lymphocytes-L. (J) Magnification of the splenic encapsulated abscess, which contains neutrophils, mononuclear cells, bacteria, and necrotic cellular debris. Sections were stained with H & E. Scale bars: 10 μm (A, E, F, J), 50 μm (B & G), 100 μm (D & I) and 500 μm (C & H). Data are representative of one experiment (n = 4 per group).
Fig 3.
Illustrations of the gating strategy employed in the immunophenotyping of B cells, NK cells, and monocytes.
Lymphocytes and monocytes were gated based on forward and side scatter characteristics. B cells were CD3-CD4-CD8-, NK cells were CD3-CD8+, and monocytes were defined as CD3-CD4dim. All gates were set using respective isotype controls.
Fig 4.
Immune cell frequencies in PBMCs of BALB/c mice infected with B. pseudomallei.
(A) B cell (B) NK cell and (C) monocyte frequencies in PBMCs isolated from uninfected, OB- and OS-infected mice after 60 days of infection. Data representative of two independent experiments (B-D; n = 6 per group). Scatter dot plots show the median value (line), the interquartile range (whiskers). P values were calculated using Mann-Whitney U test. *P<0.025, **P<0.005, ***P<0.0005 after Bonferroni correction for 2 comparisons.
Fig 5.
PD-1 and CTLA-4 expressions on Singlet/FVS 510-/Lymph/CD3-/CD4-/CD8- B cells.
Representative contour plot of (A) PD-1 and CTLA-4 expressions on B cells of uninfected, OB-infected and OS-infected mice after 60 days of infection. (B) PD-1+ and (C) CTLA-4+ percentage of uninfected, OB-infected and OS-infected mice. Data are pooled from two independent experiments (A-C; n = 6 per group). Scatter dot plots show the median value (line), the interquartile range (whiskers). P values calculated using Mann-Whitney U test. *P<0.025, **P<0.005, ***P<0.0005 after Bonferroni correction for 2 comparisons.
Fig 6.
PD-1 and CTLA-4 expressions on Singlet/FVS 510-/Lymph/CD3-/CD8+ NK cells.
Representative contour plot of (A) PD-1 and CTLA-4 expressions on NK cells of uninfected, OB-infected and OS-infected mice after 60 days of infection. (B) PD-1+ and C) CTLA-4+ percentage of uninfected, OB-infected and OS-infected mice. Data are pooled from two independent experiments (A-C; n = 6 per group). Scatter dot plots show the median value (line), the interquartile range (whiskers). P values calculated using Mann-Whitney U test. *P<0.025, **P<0.005, ***P<0.0005 after Bonferroni correction for 2 comparisons.
Fig 7.
PD-1 and CTLA-4 expressions on Singlet/FVS 510-/Monocyte/CD3-/CD4dim monocytes.
Representative contour plot of (A) PD-1 and CTLA-4 expressions on monocytes of uninfected, OB-infected and OS-infected mice after 60 days of infection. (B) PD-1+ and (C) CTLA-4+ percentage of uninfected, OB-infected and OS-infected mice. Data are pooled from two independent experiments (A-C; n = 6 per group). Scatter dot plots show the median value (line), the interquartile range (whiskers). P values calculated using Mann-Whitney U test. *P<0.025, **P<0.005, ***P<0.0005 after Bonferroni correction for 2 comparisons.